This article reports on a learning community that requires acting together in order to perform and to learn, an organization of shared activity across people and through time that we call ensemble learning. We present a descriptive analysis of ensemble learning in a high school marching band performance season, following how "The Show" was designed by instructors, translated into coordinate "dots" for band members, then learned and "cleaned" by the ensemble. We investigate aspects of representational and social infrastructure that supported ensemble learning in activity, and how they shifted in relation to emergent goals of learners over the course of the season. The dynamic, multi-party performances under the changing spatial and social conditions that were the object of the band's learning (marching competitions over the course of the season) leveraged diverse physical and social perspectives on learning and activity, and interactional and representational routines evolved over the course of the season. Additionally, the elective nature of the activity supported the emergence of practice-linked learning and teaching identities. We use the case study to extend similar accounts of ensemble learning and learning communities, and consider how our findings might inform design when restoring or building new ensemble learning environments.